The current study investigated the influence of selection for body weight (BW) on growth curve parameters in two lines of Japanese quail through a mixed model approach. Live BWs of 1400 Japanese quail were recorded at 3-day intervals from hatching to 42 days of age. Birds were distributed equally across lines (selected and control) and sexes (male and female). The asymptotic weight parameter (β0) values were always higher in Gompertz than Richards models in both lines. The values of β0 were higher in the selected than control lines and in females than males across models. Differences were found in the inflection point for age and weight across lines and sexes. Values of the growth rate parameter (β2) ranged from 0.06 to 0.10 in both models, favouring males over females in both lines. Lower weights at the inflection point of both models were observed in the control line. Determination coefficient (R2) of both models in different genetic groups and sexes was similar. Mean square error (MSE) values of the Gompertz model were lower for females in selected v. control lines. In contrast, MSE values of the Richards model were lower for selected males v. control males. According to the criteria of choice (highest R2 and lowest MSE, Akaike information criterion and Bayesian information criterion), the Richards model was considered the best fitting model for the growth data of males, while the Gompertz model was the best for growth data of female quails in both lines.

Knowledge of growth patterns of an animal species is fundamental to understand their life history. This information is also used to help define population boundaries of threatened cetaceans, such as the Franciscana dolphin, Pontoporia blainvillei. A total of 108 Franciscana dolphins incidentally captured in artisanal fishing nets in estuarine and marine coastal waters of the northern part of the Franciscana Management Area IV (North FMA IV), Argentina, were studied. The objective of the present paper was to study age and growth parameters of Franciscanas from North FMA IV and to compare these parameters between estuarine and marine potential populations within this area. We used von Bertalanffy and Gompertz growth curves to model growth trajectories. The estimated asymptotic lengths demonstrated that Franciscana dolphins from this area were smaller (females: 136.3 cm and males, 122.1 cm) than southern FMA IV values previously published. They also showed the reverse sexual size dimorphism that is known across their range. However, the estimated asymptotic length was not statistically different between the estuarine and marine females within the study area. In spite of this, the fact that the northern forms of the FMA IV were smaller than the southern specimens supports the hypothesis of more than one population of the species within this management area. The North FMA IV has the highest reported mortality levels of Franciscana dolphins within the FMA IV; these results are relevant to the knowledge base of Franciscana dolphins in the region.

An improved understanding of the effects of nitrogen (N) on crop–weed interactions is needed for the development of integrated weed management systems where responsible use of N fertilizers is considered. Field experiments conducted in 1999 and 2000 at two locations in eastern Nebraska quantify the effects of N and increasing duration of weed interference on corn growth and development. A naturally occurring population of weeds was allowed to compete with the corn crop for increasing lengths of time and at three rates of N application (0, 60, and 120 kg N ha−1). Weed interference and withholding applied N increased the time to 50% silking by an average of 3.9 and 2.9 d, respectively. Regardless of treatments, relative growth rates of corn leaf area and biomass were maximized between the V1 and V2 growth stages of corn and increased linearly with N rate but were affected to a lesser extent by weed presence. The improvement in early season corn growth with addition of N resulted in greater leaf area, biomass, and height, which improved the competitive ability of corn against weeds. Reductions in maximum corn leaf area and height due to weed interference usually began earlier and were more extensive at reduced rates of N. Partitioning of biomass to reproductive structures increased with N during reproductive stages, likely contributing to greater harvest indices at the end of the season. Results from this study indicate that the effects of N fertilization on early-season crop growth provided a competitive advantage for corn relative to weeds, thereby increasing the length of time that weeds could compete with a crop before removal was required, but further research is needed to identify mechanisms regarding improved crop tolerance to weeds.

The popular technique of estimating ages of deposits from sizes of lichens continues despite valid criticism, and without agreement on range of utility, treatment of error, and methods of measurement, sampling, and data handling. A major source of error is the assumption that the largest lichen(s) colonized soon after deposition and will survive indefinitely. Recent studies on lichen mortality suggest that this assumption is untenable. Meanwhile, the use of “growth curves” constructed from independently dated substrates is problematic for many reasons, but this has not prevented the publication of baseless claims of accuracy and ages that are extrapolated well beyond data. Experiments indicate that numeric lichenometric ages are not reliable, and in general do not advance the cause of Quaternary science. There are a few studies suggesting reliability, and indeed there may be cases where lichens and growth curves actually provide realistic numerical ages. But it cannot be foretold which lichen assemblages will provide good ages and which bad ages. The logical conclusion is that no assumption of good ages can be made, and that it is folly to assign numerical ages to a deposit on the basis of lichen sizes.

Previous research has shown that childhood body size is associated with blood pressure in adulthood, and that early and rapid growth rates are correlated with adverse cardiovascular outcomes. Our objectives are to estimate associations between childhood body size growth parameters and adult blood pressure, and to examine the effect of early attainment of critical growth milestones on adult blood pressure, relative to normal or late attainment. Lifetime height and body mass index (BMI) measurements in childhood, and systolic blood pressure (SBP) and diastolic blood pressure (DBP) measurements in adulthood are taken from participants in the Fels Longitudinal Study. Childhood growth curves are estimated separately for stature and BMI using the Preece–Baines and third-degree polynomial models, respectively. Associations between the resulting parameter estimates and adult blood pressure are then examined using linear mixed models. Our findings show that the ages of achievement of the stature-based growth onset and peak velocity, as well as the age of achievement of the BMI-based adiposity rebound, are negatively associated with adult blood pressure, implying that early height or BMI growth can lead to increased blood pressure in adulthood. There were subtle differences in these relationships based on age and gender, and also between SBP and DBP. These results expand on the existing literature, showing that not only childhood body size, but also the timing of childhood growth can have a deleterious effect on adult cardiovascular health.

T-bar anchor tags and Petersen discs were used during a preliminary mark–recapture experiment in the wild on 268 Octopus vulgaris. Discs, despite causing some injuries, were characterized by a quicker healing (within 5 days) and a higher retention rate than T-bar tags (about 97% versus 22%, respectively), therefore they were considered the best technique for tagging the animals in the subsequent growth studies. From 2010 to 2013, a total of 1604 O. vulgaris (74.4% with a total weight <300 g) were tagged with discs and released in an area of the central western Sardinian Sea (western Mediterranean Sea). Ninety-one specimens were recaptured after 4–63 days of freedom, 59 of which (31 males and 28 females) showed positive growth increments after a minimum time of 8 days at liberty. In general, a high individual variability (0.96–9.09 g day−1) and higher mean daily growth rates in females (3.07–3.65 g day−1) than in males (2.08–2.98 g day−1) were recorded, but this difference was not statistically significant. Using tag–recapture data, the first exponential growth curves for both sexes of Octopus vulgaris of small–medium size from the Mediterranean Sea were obtained, and compared with those available in the literature for the species.

Genealogical and live body weight monthly records from 790 sheep of the Chiapas breed born between 1991 and 2004 were used to characterize the growth curve and estimate (co)variance components for the parameters (A, k and b) of the Gompertz function. The pedigree structure consisted of 790 sheep, including 45 rams and 379 ewes. Estimation of (co)variance components for each growth parameter was achieved using a univariate animal model with the restricted maximum likelihood (REML) method. Estimated values of heritability were: A (adult weight) 0.21 ± 0.06; b (integration constant) 0.25 ± 0.07; k (maturity rate) 0.16 ± 0.06; age at the inflexion estimated as (ln(b)/k) 0.24 ± 0.07; and absolute growth rate as [k*(0.368*A)* ln(A/0.368*A)] 0.22 ± 0.07. The growth of males was 24% (P < 0.05) faster than that of females; adult weight was 25 ± 0.7 kg for males and 23 ± 0.7 kg for females; absolute growth was 59 ± 2 g and 44 ± 2 g per day for males and females respectively. The Chiapas breed of sheep is a small animal with a slow growth curve, probably due to its adaptation to the environmental conditions where it lives. Growth curve can be modified through selection.

We describe methods to fit structured latent growth curves to data from MZ and DZ twins. The well-known Gompertz, logistic and exponential curves may be written as a function of three components – asymptote, initial value, and rate of change. These components are allowed to vary and covary within individuals in a structured latent growth model. Such models are highly economical, requiring a small number of parameters to describe covariation across many occasions of measurement. We extend these methods to analyse longitudinal data from MZ and DZ twins and focus on the estimation of genetic and environmental variation and covariation in each of the asymptote, initial and rate of growth factors. For illustration, the models are fitted to longitudinal Bayley Infant Mental Development Scale data published by McArdle (1986). In these data, all three components of growth appear strongly familial with the majority of variance associated with the shared environment; differences between the models were not great. Occasion-specific residual factors not associated with the curve components account for approximately 40% of variance of which a significant proportion is additive genetic. Though the growth curve model fit less well than some others, they make restrictive, falsifiable predictions about the mean, variance and twin covariance of other (not yet measured) occasions of measurement. Twin Research (2000) 3, 165–177.

Growth trajectories play a central role in life course epidemiology, often providing fundamental indicators of prenatal or childhood development, as well as an array of potential determinants of adult health outcomes. Statistical methods for the analysis of growth trajectories have been widely studied, but many challenging problems remain. Repeated measurements of length, weight and head circumference, for example, may be available on most subjects in a study, but usually only sparse temporal sampling of such variables is feasible. It can thus be challenging to gain a detailed understanding of growth patterns, and smoothing techniques are inevitably needed. Moreover, the problem is exacerbated by the presence of large fluctuations in growth velocity during early infancy, and high variability between subjects. Existing approaches, however, can be inflexible because of a reliance on parametric models, require computationally intensive methods that are unsuitable for exploratory analyses, or are only capable of examining each variable separately. This article proposes some new nonparametric approaches to analyzing sparse data on growth trajectories, with flexibility and ease of implementation being key features. The methods are illustrated using data on participants in the Collaborative Perinatal Project.

The individual growth variability of passive integrated transponder tagged sea bass was studied using data sets from two different experiments. In experiment 1 (n = 485), fish submitted to different photoperiod regimes were held in fourteen groups of individual weight of 88 ± 13 g (mean ± SD). In experiment 2 (n = 748, initial weight 243 ± 30 g) fish were held in fifteen groups and had either free or restricted access to diets with three lipid levels. After adjustment for treatment and tank effects, individual growth curves were analysed using multivariate analysis (principal component analysis and clustering) and were modelled using the summary statistics technique. Different growth profiles where characterized. All of them appeared to be curvilinear. They differed in their level (initial and final weight), slope (slope, specific growth weight, gain) and especially the ratio of males, which showed sexual growth dimorphism. The fish with similar initial weight proved to have very different growth performances, regardless of the treatment effect. Within the same sex, part of the variability between the growth profiles could be explained by differences in the social interactions and in the genetic potential of growth among individuals.

Rapid rate of recovery has been associated with better outcome following closed-head injuries, but few studies have compellingly demonstrated this. This study used growth curve analyses of Disability Rating Scale (DRS) scores at acute hospitalization discharge, 1, 3, and 6 months post injury in a sample of 55 patients with a closed-head injury. Six month post-injury outcome measures were taken from significant other (SO) responses on the NYU Head Injury Family Interview (NYU-HIFI) including severity and burden ratings of affective/neurobehavioral disturbance, cognitive deficits, and physical/dependency status. Rate of recovery (linear and curvilinear recovery curve components) was significantly related to the level of affective/neurobehavioral severity, and the severity and burden of SO-perceived cognitive deficits. Only the intercept of the DRS recovery curve was associated with the SO-perceived severity and burden of physical/dependency status. Growth curve modeling is a meaningful and powerful tool in predicting head injury outcome. (JINS, 2001, 7, 457–467.)

The Indian false vampire bat Megaderma lyra produces a single young under captive conditions, which is altricial at birth. Empirical growth curves were derived by measuring length of forearm, body mass and length of the total gap of the fourth metacarpal–phalangeal joint. Length of forearm and body mass followed a linear pattern of growth until day 28 and subsequently reached stability. The length of the total gap of the metacarpal–phalangeal joint initially showed a linear increase up to 4 days, followed by a linear decrease until 34 days when it closed. A quantitative method of estimation of age was derived from values of length of forearm and length of the total gap of the fourth metacarpal–phalangeal joint during the preflight (first 28 days) and postflight stages, respectively. Width of the 95% confidence level was ± 1.2 days at a mean length of forearm of 51.6 mm, and ± 0.07 days at a mean length of the total gap of the fourth metacarpal–phalangeal joint of 1.89 mm. Initiation of flight occurred 24 days after birth. At 28 days of age, young were able to forage on their own. There was no significant difference in the growth pattern of young held in captivity compared to that of young grown under natural conditions.

Polynomial models with random regression coefficients were used to describe cumulated food intake and gain as a function of number of days on test for gilts and castrated male pigs which were on test from 30 to 115 kg live weight. Growth rate and daily food intake were expressed as the derivative of the curves. The applied models allowed a separation of between and within animal variation. Confidence limits for average curves and prediction limits for individual curves were also obtained. A similar model was used to describe gain as a function of cumulated food intake. From this function food efficiency was obtained. The application of the results in stochastic simulation models is discussed.

Growth rate and daily food intake had a more curvilinear progress for castrated males than for gilts. It was estimated that 98% of the castrated males and 96% of the gilts had a lower growth rate at day 80 than at day 50; 74% of the castrated males and 48% of the gilts had a lower daily food intake at day 100 than at day 80. On average food efficiency of gilts was higher than food efficiency of castrated males and the difference increased through the test period.

Two synthetic lines of rabbits were used in the experiment. Line V, selected on litter size, and line R, selected on growth rate. Ninety-six animals were randomly collected from 48 litters, taking a male and a female each time. Richards and Gompertz growth curves were fitted. Sexual dimorphism appeared in the line V but not in the R. Values for b and k were similar in all curves. Maximum growth rate took place in weeks 7 to 8. A break due to weaning could be observed in weeks 4 to 5. Although there is a remarkable similarity of the values of all the parameters using data from the first 20 weeks only, the higher standard errors on adult weight would make 30 weeks the preferable time to take data for live-weight growth curves.

The Gompertz equation was used to compute growth curves for three groups of ostriches (Struthio camelus), from Oudtshoorn in South Africa, the Namib desert in Namibia and from Zimbabwe. All were reared under typical intensive farm conditions with ad libitum feeding. There were no significant differences in mature mass between regions but the maximum daily weight gain for males occurred later (day 163) for Oudtshoorn birds, compared with day 121 for Namibian and day 92 for Zimbabwean. Oudtshoorn females reached maximum rate of gain on day 175 compared with day 115 for Namibian and day 114 for Zimbabwean. Comparisons might prove important when planning programmes for the genetic improvement of commercial flocks, but possible influences of food composition and environment should be investigated.